The report was released Monday, nearly one year after then-Secretary of State Hillary Clinton, under congressional questioning over the nature of the attack, shouted at lawmakers: “What difference, at this point, does it make?”

The administration initially claimed the attack sprung out of a protest, but has since given a more complicated assessment. Still, administration officials all along have downplayed Al Qaeda involvement, recently seizing on a New York Times report that supported those claims.

While the report does not implicate Al Qaeda “core” -- the leadership believed to be in the Pakistan region -- it does blame some of the most influential Al Qaeda branches, including Al Qaeda in the Arabian Peninsula (AQAP) and Al Qaeda in the Islamic Maghreb (AQIM).

“Individuals affiliated with terrorist groups, including AQIM, Ansar al-Sharia, AQAP, and the Mohammad Jamal Network, participated in the September 11, 2012, attacks,” the report said. The militant Ansar al-Sharia was, separately, labeled by the State Department as a terror group last week, in part over its alleged involvement in the Benghazi strike.

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The Senate committee report stressed that the intelligence still suggests the attack was not “highly coordinated,” but rather “opportunistic” – possibly put in place in “short order” after protests over an anti-Islam film elsewhere in the region.

“It remains unclear if any group or person exercised overall command and control of the attacks,” the report said. The report, though, reiterated that there was no protest in Benghazi before the attack.

The Senate panel report also dove extensively into what went wrong at the U.S. mission in Benghazi before the attack. The committee determined the attack was “preventable” and the administration failed to respond to “ample” warnings that security was deteriorating before Sept. 11, 2012.

The report faulted the State and Defense departments. It also cited the failure of the Obama administration to "bring the attackers to justice."

Specifically, the report said the intelligence community provided “ample strategic warning” that security in eastern Libya was deteriorating and U.S. personnel “were at risk.” The report said multiple “tripwires” were crossed signaling security problems, and the State Department should have increased its security posture in response. This included an Aug. 16, 2012, cable from Ambassador Chris Stevens raising security concerns, and prior attacks on westerners in Benghazi.

The report also detailed a possible failed ambush, where attackers tried to lure the CIA into the hospital where Stevens' body was being held.

The CIA did not take the bait.

"The committee worked on a bipartisan basis to investigate the various allegations that have come out since the terrorist attacks in Benghazi in September 2012 and to get to the truth about what happened leading up to, during and after the attacks,” Senate Intelligence Committee Chairwoman Dianne Feinstein, D-Calif., said in a statement, adding she hopes the report puts “conspiracy theories” to rest.

Sen. Saxby Chambliss, R-Ga., top Republican on the panel, also said the report provides “needed and deserved answers.”

“In spite of the deteriorating security situation in Benghazi and ample strategic warnings, the United States Government simply did not do enough to prevent these attacks and ensure the safety of those serving in Benghazi,” he said.